Original Contribution
Changing trends in the distribution of the histologic types of lung cancer: a review of 4,439 cases

https://doi.org/10.1016/j.anndiagpath.2006.04.006Get rights and content

Abstract

Lung cancer is the second most common cancer and the leading cause of cancer death in both men and women. The purpose of the study is to explore the distribution of the 4 major histologic types of lung carcinoma and the incidence of lung cancer with reference to all other sites of cancer. The clinical and histopathologic data of 4,439 patients with lung carcinoma between January 1980 and December 2003 were reviewed. Adenocarcinoma has become the most frequent histologic type in men and women (36.8% and 46.5%, respectively), followed by squamous cell carcinoma (31.6% and 25.4%, respectively). The incidence of large cell (undifferentiated) carcinoma in men and women is 18.0% and 9.9%, respectively. The incidence of small cell carcinoma in men and women is 13.7% and 18.3%, respectively. In addition, analysis of our data indicates that lung cancer rate is decreasing, relative to all other primary cancer sites. The results of this study suggest that the incidence of lung cancer has decreased in comparison with other sources of cancer in southern Texas. This observation is consistent with the current national trends. In addition, there are significant changes in the distribution of the major histologic types of lung cancer. The results of this study may portend important changes in the selection of targeted therapy and patient management.

Introduction

Lung cancer is the second most common cancer and the leading cause of cancer death in both men and women in the United States. According to the American Cancer Society, in the year 2004, there were approximately 173,770 new cases of lung cancer (93,110 among men and 80,660 among women). Lung cancer–related deaths in 2004 totaled an estimated 160,440 cases (91,930 among men and 68,510 among women). Over the last few years, these rates appear to have decreased, especially among men and, to a lesser extent, among women [1], [2], [3], [4], [5], [6], [7], [8], [9].

The incidence of all 4 major histologic types of lung cancer has also changed significantly over the last few years [6], [7], [8], [10]. The 4 major histologic types of lung cancer include adenocarcinoma, squamous cell carcinoma, small cell carcinoma, and large cell (undifferentiated) carcinoma, which, in aggregate, account for approximately 99% of all cases of primary lung cancer [11].

Our observation of the changing trends in the distribution of the major histologic types of lung cancer over the last several years and the recent reports of the decline in lung cancer incidence prompted our intensive clinical, histopathologic, and statistical review of lung cancer cases between 1980 and 2003 in southern Texas. The data will be compared with those of our previous study of the midsouthern region of the United States, which derived from a review of 4,928 lung cancer cases from 1964 to 1985 [12]. The results of this study illustrate the need for careful analysis of lung cancer data and its contribution to understanding the etiology of the different types of lung cancer and may portend important changes in the selection of targeted therapy and patient management.

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Materials and methods

The University of Texas Medical Branch in Galveston, Texas, is the oldest of the 4 health science centers in the University of Texas system. The University of Texas Medical Branch has approximately 800 beds, serves approximately 220 counties in southern Texas, and offers comprehensive medical, surgical, rehabilitative, subspecialty, pathologic, therapeutic, and consultative services for adult patients. Over the 24 years covered by this study, the total number of patient admissions has been

The decline in the incidence of lung cancer

Over the 24 years selected for our study, the number of lung cancer cases decreased, relative to all other sources of cancer (Table 1). The total number of all cancer cases and the absolute number and percentage of lung cancer cases are indicated by year in Table 1. In the early 1980s, approximately 18.5% of all cancer cases were lung cancer, yet in the late 1990s to early 2000s, approximately 13.5% of all cancer cases were from lung.

Changes in histologic types of lung cancer

The number and average patient age for cases of each of the 4

Discussion

Lung cancer remains the leading cause of cancer death in both men and women in the United States, although the incidence rates of lung cancer among men have declined, whereas the incidence rates of lung cancer among women have plateaued or are slightly decreased [2], [3], [4], [5], [6], [7], [8], [9]. Despite the incidence rates of lung cancer being still higher among men than among women, the gap between men and women has narrowed [3], [4].

A decrease in the incidence of lung cancer in men was

Conclusions

The results of this study indicate that between 1980 and 2003, lung cancer incidence in southern Texas has decreased. Furthermore, our results confirm the decreasing incidence of lung cancer as compared with other sources of cancer in southern Texas. This observation is consistent with the current national statistics. This recent decline may be attributed to the decreased prevalence of smoking among men and women. In addition, there are marked changes in the distribution of the major histologic

Acknowledgment

The authors thank Laura Lemley for her help in preparing the manuscript.

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